This application claims priority to German Application No. 100 27 902.3, filed Jun. 6, 2000, herein incorporated by reference in its entirety.
1. Field of the Invention
This invention relates to an industrial truck with a lifting apparatus, in particular a lifting mast, and a driver""s workplace.
2. Technical Considerations
The lifting apparatuses on industrial trucks of the prior art typically have a plurality of telescoping devices. Under certain conditions, the operator of an industrial truck can reach forward with one hand and touch the moving parts of the lifting apparatus while the lifting apparatus is actuated, for example by leaning or bending forward from the driver""s workplace. The driver""s fingers or hands can thereby be injured at shear points or pinch points in the vicinity of the moving parts of the lifting apparatus.
To prevent such injuries, the prior art teaches that the shear points and pinch points on the moving parts of the lifting apparatus can be protected against being touched. In the prior art, the shear points and pinch points are frequently protected with covers, protective grates, or panels, e.g., glass or Plexiglas panels. However, safety devices of this type frequently block or interfere with the driver""s view of the lifting apparatus and the load holding means, such as a lifting fork with prongs, located on the lifting apparatus. Moreover, as accident statistics show, safety devices of the type described above frequently do not completely prevent injuries to the operator when the operator touches the moving lifting apparatus.
It is also possible to increase the distance between the driver""s workplace and the lifting apparatus so that from the driver""s workplace, the operator can no longer touch the lifting apparatus while simultaneously actuating the lifting apparatus. A distance of this magnitude, however, means that the overall dimensions of the industrial truck become larger or, if the position of the driver""s workplace is unchanged, results in an increased weight of the front part of the lifting apparatus with a corresponding increase in the load moment. An industrial truck with an increased distance between the lifting apparatus and the driver""s workplace therefore has a lower load carrying capacity.
Therefore, it is an object of this invention is to provide an industrial truck of the type described above in which injuries caused by the operator touching the lifting apparatus can be prevented or reduced.
The invention teaches that a safety device is provided that is effectively, e.g., operationally, connected with a drive device of the lifting apparatus and/or an actuator device of the lifting apparatus. By means of a safety device that is effectively connected with the drive device of the lifting apparatus and/or the actuator device of the lifting apparatus, it can be ensured in a simple manner that the lifting apparatus can only be operated under operating conditions in which the driver cannot touch the moving parts of the lifting apparatus. Injuries caused by touching the actuated lifting apparatus can therefore be prevented in a simple manner. The invention teaches that no safety devices are necessary on the lifting apparatus itself that interfere with the driver""s view. The driver""s workplace can also be located in the immediate vicinity of the lifting apparatus, as a result of which the front portion of the industrial truck can be kept compact and thus has a lower load moment.
In one preferred embodiment of the invention, the safety device is effectively connected with a sensor device. As a function of the signal from the sensor device, the drive device of the lifting apparatus can receive a signal and/or the actuator device of the lifting apparatus can be enabled. By means of the sensor device, it can be determined easily and reliably whether the operator is touching the lifting mast or not. The safety device allows the drive device to receive a signal or enables the actuator device of the lifting apparatus only if the driver is not touching the lifting apparatus.
In another embodiment of the invention, the sensor device is realized in the form of a safety device that is actuated by an operator""s hand. Using a sensor device of this type, it can easily be detected whether the operator""s hand is on the sensor device and the sensor device is actuated. The signal from the actuated sensor device enables or actuates the drive device and/or the actuator device of the lifting apparatus, as a result of which it can easily be ensured that the lifting apparatus can be actuated only when one of the operator""s hands is on the sensor device and the operator""s other hand is actuating the actuator device, meaning that the operator does not have any hands free to touch the moving parts of the lifting apparatus. The sensor device can thereby be located in any convenient or suitable position in the vicinity of the driver""s workplace.
In a still further embodiment of the invention, the sensor device is located on a steering device, such as a steering wheel, and detects contact by the operator""s hand with the steering wheel. With a sensor device that is located on the steering wheel, it can easily be determined whether or not the driver is touching the lifting apparatus. If the sensor device located on the steering wheel detects that one of the driver""s hands is in contact with the steering wheel and is therefore on the steering wheel, it can be ensured in a simple manner that when the actuator device of the lifting apparatus is actuated by the operator""s other hand, the operator has no hands free to touch the lifting apparatus. The lifting apparatus can thus be actuated without any risk of injury to the operator. The actuator device can advantageously be realized in the form of a joystick.
In an additional embodiment, the safety device includes an electronic control device that is effectively, e.g., operationally, connected with the sensor device, the actuator device, and/or the drive device of the lifting apparatus such that as a function of the signal from the sensor device, the signal of the actuator device can be enabled and/or the drive device can receive the signal. By means of an electronic control device, the signal of the actuator device, such as a joystick, for example, can easily be enabled to actuate the lifting apparatus or the drive device can receive a signal as a function of the signal from the actuator device only if a signal is detected by the sensor device that indicates the presence of the operator""s hand.
The sensor can be realized in the form of a sensor that detects contact by the operator""s hand with the steering wheel, such that in an operating situation in which the sensor device reports contact between the steering wheel and the operator""s hand, the signal from the actuator device can be enabled. It is thereby possible to ensure in a simple manner that only when the operator is touching the steering wheel with one hand can the operator actuate the lifting apparatus by actuating the actuator device with the other hand. This procedure ensures that the lifting apparatus can be actuated only under operating conditions in which the operator does not have any hands free to touch the moving parts of the lifting apparatus.
In another embodiment, the industrial truck is realized in the form of a driver-controlled fork lift truck with a driver""s workplace that faces the lifting apparatus. On industrial trucks of this type, in which the operator can touch the lifting apparatus by bending or leaning forward from the driver""s workplace, the safety device taught by the invention can effectively and easily prevent injuries to the operator caused by touching the lifting apparatus.